Traefik as Reverse Proxy for Grafana and Prometheus

Traefik Traefik v2
3

Ok,
I have solved this issue by myself via specifying the subpath in prometheus and grafana directly. Now it's working as expected with this configuration:

api:
  dashboard: True

entryPoints:
  web:
    address: ":80"

http:
  routers:
    prometheus-router:
      rule: "PathPrefix(`/prometheus`)"
      service: prometheus   
      entryPoints:          
        - web
    grafana-router:
      rule: "PathPrefix(`/grafana`)"
      service: grafana               
      entryPoints:                   
        - web             
    dashboard:
      rule: "PathPrefix(`/api`) || PathPrefix(`/dashboard`)"
      service: dashboard@internal
      entryPoints:
        - web
  services:  
    prometheus:
      loadBalancer:            
        servers:               
          - url: "http://127.0.0.1:9090/"
    grafana:
      loadBalancer:
        servers:   
          - url: "http://127.0.0.1:3000/"

The only thing that still doesn't work is the access to the traefik dashboard or API... if anybody has an idea, I would be happy.